Sighting apparatus for use on aircraft



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SIGHTING APPARATUS FOR USE ON AIRCRAFT Filed Feb. 10, 1959 11 Sheets-Sheet 1 Jan. 2,1940. 5. c. HORSLEY SIGHTING APPARATUS FOR 135E ON AIRCRAFT l1 Sheets-Sheet 2 Filed Feb. 10, 1939 m Na mm h mwwmw hua/Ld Q r A744,; f 9 17 wv/zmzu v Jan. 2, 1940. c HORSLEY 2,185,633

SIGI'ITING APPARATUS FOR USE ON AIRCRAFT Filed Feb. 10, 1939 ll Sheets-Sheet 3 PM; Q01 44% i IE. CJHORSLEY 2,185,633.

SIGHTING APPARATUS FOR USE ON AIRCRAFT I Filed. Feb. 10, 1939 ll Sheets-Sheet 4 E. c. HQRSLEY SIGHTING APPARATUS FOR USE ON AIRCRAFT Jan. 2, 1940.

Filed Feb. 10, 1939 11 Shets-She t 5 fuwd 0x40 44/ 44 4 Jan. 2, 1,940. E. C.'HORSLEY I S'IGHTING APPARATUS FOR USE ON AiBCRAFT Filed FebLlO, 1939 11 Sheets-Sheet s 1940- E. c. HORSLEY v 2,185,633

SIGHTING APPARATUS FOR USE ON AIRCRAFT Filed Feb. I0, 1939 11 Sheets-Sheet 'r 5% WV Ema! Jan. 2, 1940. E. c. HORSLEY SIGHTING APPARATUS FOR USE ON AIRCRAFT l1 Sheets-Sheet 9 Filed Feb. 10, 19:59

1940- E. c. HORSLEY 2,185,633

SIGHTING APPARATUS FOR USE ON AIRCRAFT Filed Feb. 10, 1939 11 Sheets-Sheet l0 Jan. 2, 1940.

E. C. HORSLEY SIGHTING APPARATUS FOR USE ON AIRCRAFT 11 Sheets-She-t 11 Filed Feb. 10, 1939 Ha r,

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Patented Jan. 2, 1940 PATENT orrica SIGHTING APPARATUS FOR USE ON AIRCRAFT Edward Cecil Horsley, London, England Application February 10, 1939, Serial No. 255,672 In Great Britain April 8, 1929 I 19 Claims. (01; 33 46.5)

This application corresponds to the secret patents of Edward Cecil Horsley, Serial No. 10803/29, Serial .No. 11366/29 and Serial No. 35515/30, which were filed in Great Britain on April 8, 1929, April 12, 1929 and November 26, 1930, respectively.

This invention relates to sighting apparatus for-- use on aircraft. The invention is concerned with bomb sights of the type comprising adjustable I members representing the vector quantities of air speed i. e., the speed of the bomb sight relative to the surrounding air, wind speed, i. e., the speed of the air relative to the ground and ground sp-eedQi; e., ther'elative speed between the bomb sight and theground.

Generally, such a bomb sight comprises an air speed member, a wind member and a drift member which are plvotally connected together and are adjustable in length and which are furthermore arranged horizontally, together with a rear ing garduated from nought to 360 and showing the points of the compass. In addition, there is an air speed bar pointer or lubber mark (vertically above the axisof the air speed bar), a drift bar pointer (which moves with the drift bar) reading against the bearing plate and a drift scale and wind gauge bar hinged to the altitude bar. The air speed bar pointer is marked on the drift scale which is graduated up to on each side of zero for reading the drift angle and is carried on the bomb sight frame. The wind bar gauge can be folded down over a glass covering the bearing plate and isused to determine the wind elements, it being arranged to move in line with the drift bar.

According to one feature of the present invention there is provided a bomb sight comprisingthe relatively adjustable members representing the vector quantities of air speed, wind speed and drift for determining the sighting line, characterized by means automatically to efiect a correction of the sighting line for the trail angle of a bomb when the air speed member is adjusted for air speed. Furthermore, means is comveniently provided for eflecting a trail angle correction of the sighting line for bombs of difierent terminal velocities.

According to a further feature of the invention. the correction for trail angle is applied to an upstanding altitude member or to a back sight thereon. Preferably, this correction is obtained by a coupling between the altitude member and the air speed member such that the former moves according to a function of the trail angle and air speed. The means for adjusting the correction for bombs having different terminal velocities is conveniently arranged to vary this cou- According to another feature of the invention,

the altitude member aforesaid is pivotally moun ed in a position displaced from the origin or trail point of the bomb sight. In this manner a correction for trail angle as aforesaid may be arranged to hold good for various adjustments of the back sight on the altitude member. Alternatively, for this purpose, the altitude member is so shaped that the correction for trail angle is maintained for adjustment of the back sight on the altitude member.

For the adjustment of the air speed member there is conveniently provided a handle with which there is associated a friction brake releasable by the hand wheel for normally locking the air speed member in the adjusted position.

Yet another feature of the invention consists in the provision in a bomb sight as aioresaid of an additional adjustable member representing target speed (i. e., the speed of the target relatively to the ground). This target speed member is conveniently pivoted at one of the connections between the air speed member, the wind member and the drift member, and in the preferred construction is pivoted to the drift member at a part displaced from the connection of the drift member to the wind member.

According to a further feature of the invention the altitude member with the back sight thereon is coupled to the drift member so as to be rotatable therewith about a vertical am which is laterally movable with respect to the bomb sight base.

The altitude member is plvotally mounted for iwtly comprises upper and lower parts, wh ch 5' upper part is tiltable with respect to the lower part on the bomb sight frame and the slider which carries the altitude member comprises two parts movable respectively on the upper and lower parts of the'target speed member. The two parts of the target speed member'may be interconnected for, joint rotation with the upper part rotatably carried ina tiltable frame.

A further feature of the invention consists of a bomb sight as aforesaid havinga compass with its bowl rotatably mounted and geared to the wind member and a bearing plate rotatable at the top of the bowl, wherein the bearing plate and the bowl are each provided with a toothed gear, one of which meshes with a pinion fast on a rotatable adjusting shaft and the other with a second pinion connected to said shaft through a disengageable clutch.

The invention will now be further described with reference to specific embodiments and illustrated by wayof' example in the accompanying drawings, in which Figure 1 is a general arrangement side elevation of a course setting bomb sight incorporating one form of the present invention, parts being broken away or omitted to show the mechanism for the correction of trail angle;

Figure 2 is a similar View to Figure 1 with other parts broken away to show the compass bowl mechanism;

Figure 3 is a diagrammatic view of mechanism shown in Figure 1;

Figure 4 is a view similar to Figure 3 showing a modification;

Figure 5 is a sectional elevation of a con structional detail;

Figures 6, 7 and 8 are respectively a front elevation, a sectional elevation at right-angles thereto and a sectional plan of a constructional detail;

Figures 9 and 10 are respectively a sectional elevation and a sectional plan of another detail;

Figure 11 is a diagram showing how the pivot position of the altitude member is obtained;

Figure 12 is a diagrammatic perspective view showing the vector elements and general geometry of the bomb sight, including the target speed vector;

Figure 13 is a sectional elevation showing details of the mounting of the target speed member and altitude member, the section being taken on line 5-43 of Figure Figure 14 is a plan of. the upper part of the mechanism shown in Figure 13;

Figure 15 is a section on line l5--I5 of Figure 13;

Figures 16 and 17 show in elevation'and plan respectively a modified construction of the bomb sight;

Figure 18 is a sectional elevation of part of the bomb sight showing means for the adjustment of the compass bowl and bearing plate;

Figure 19 is an elevation of the adjusting means looking from the right in Figure 18, the bearing plate and compass bowl being removed;

Figure 20 is a section on line -213 of Figure 18, and

Figures 21 and 22 show details.

Like references indicate like parts throughout the figures or the drawings.

'DnFnwi -wv v rv-n of the drawings, the bomb sight comprises an air speed bar 25 adjustable lengthwise in the frame of the bomb sight indicated at 28, a wind bar 21 which is also adjustable in length and is provided with a spindle 28 by means of which it is rotatably mounted in the air speed bar, a drift bar 29 slidable in a block 30 pivoted on the wind bar 21, a fore sight being provided as indicated at 3 l. The drift bar 29 is pivotally mounted about the axis 32 on the bomb sight frame. An altitude bar 33 with an adjustable back sight 34 thereon is pivotally mounted at 38.

The air speed bar 25 is provided with a rack 35 which is engaged by means of a pinion 36 fast on a transverse spindle 3i rotatably mounted in the bomb sight frame. A cam 39 is mounted on this spindle and the contour of this cam is calculated according to a law or function correlating trail angle and air speed and is arranged to apply a correction for the trail angle to the altitude bar by tilting it in a fore and aft plane. The correlation between trail angle and air speed is determined from ballistic tables I computed from actual experiments in which bombs are dropped.

and measurements taken. The arrangement is such that as the air speed bar 25 is adjusted lengthwise for air speed the cam operating through a transmission mechanism (hereinafter I describedl'tilts the altitude'bar about its pivotal mounting to give a correction for trail angle dependent on the air speed. The transmission mechanism between the cam and the altitude bar is adjustable to enable the correction to be adjusted for bombs having different terminal ve- 'locities.

which at its upper and carries a roller d5 engaging a curved surface ii of an arm 58 which is connected to the altitude bar 33.

The link 45 slides in a drum 49 rotatabiy mounted in the bomb sight frame and this drum carries an index 50 registering with a terminal velocity scale 5! faxed on the bomb sight frame to enable the linkto be set at different inclinations for bombs having different terminal velocities. Springs 52 and 53 are provided for keeping the rollers 45 and 4B in contact with the curved surfaces dS and '37 respectively. The block ll is split at 56 and the two parts are adjustable towards and away from one another by means of a set screw 55.

A hand wheel 5'! (see Fig. 5) is mounted on they spindle 2'! and has an air speed scale 53 cooperating with an index on a fixed rim 59 on the bomb sight frame. That partof the handle carrying the scale has a conical surface 68 engaging with the inner surface of the rim 59 under the action of a spring 6| so that the spindle 37 is frlctlonally held in position. When it is desired to adjust the air speed bar to a new position the hand wheel 51 is pressed inwardly to disengage the surface so from the rim E9 and is then turned as required. The axial movement of the hand wheel may be accommodated by allowing for a Small axial movement of the hand wheel on the spindle 37 or by allowing for a small axial movement of this spindle in the bomb sight frame. The rotary drum 9 for adjusting the transmission mechanism for bombs of different terminal vclw with a second hand wheel and a second friction brake operating in a similar manner to that described for adjusting the air speed scale, Orwith a jaw or other type of clutch.

The operation of the arrangement just described is as follows: With the adjustment of the air speed bar the cam 39 assumes a definite position for each particular air speed setting and therefore the angular. motion of the block 4! about its fulcrum is thereby controlled by the air speed setting. Inclination of the drum d9 according to terminal velocity of the bomb determines the position of the lower roller 44 on the curved surface 43. The combined motions control the.

total movement of the link 45 for operating the altitude bar 33. Once the drum 49 is set according to the terminal velocity of the particular,

the altitude bar.- Also, assuming the air speed is set tozero the block 4! has a neutral position with the curved surface concentric with the axis of the drum 49, and the altitude bar is vertical for any position of the roller 44, that is, for any terminal velocity setting.

In the modified arrangement shown in Figure 4 the cam 38 is engaged by a roller 62 mounted at one end of a slide block 83, which is mounted in a guide 64 in the bomb sight frame and is pressed towards the cam 39 by means of a spring 65 anchored on the bomb sight frame. The other end of the slide block 83 is pivotally connected at B8 to one end of a link Bl, the other end of which is pivotally connected at 63 to a slide block .69 movable in a slot 70 in a rotatable disc 1 i. The

slot 70 is curved and the general direction of the slot can be adjusted by rotating the disc ll by hand. An index '52 fixed on the bomb sight frame is arranged to register witha terminal velocity scale 13 on the disc H to enable the slot 10 to be wheel, as in the preceding construction, the cam 39 being rotated, assumes a definite position for each air speed setting, and therefore the slide block 53 also has a definite position according to this setting and determines the position of the pivot 55. The position of the pivot 68 is controlled by the inclination of the curved slot 10 according to the terminal velocity. The combined adjustments control the movement of the link 75 which correspondingly alters the inclination of the altitude bar.

The terminal velocity disc '11 is set to the terminal velocity of the particular bomb to be used, and when once set, varying settings of the air speed determine the correct inclination of the altitude bar. The arrangement is such that, when the terminal velocity is set to infinity. the curved slot '10 becomes approximately neutral and the altitude bar becomes vertical. In this setting, movement of the cam imparts no vertical component to the aititude bar crank, and the altitude bar remains in a vertical position. The arrangement is also such that for any terminal velocity setting, assuming the air speed is set to zero, the slide block 59 moves to the centre of the disc 75. In chisseii-Lug', the link 37 comes into a neutral position and the altitude bar becomes vertical.

In obtaining compensation for trail angle for varying altitude settings according to the present I invention, advantage is taken of the discovery that if. as'shown in Figure 11, trail angles at, 62, 93 for the same air speed and for different heights, say above 2,500 feet, are plotted in relation to a common trail point 0, a. fair straight line PiP2---P3, can be drawn through the intersec tion of the trail angle lines with the horizontal height lines, and the fair straight line, if produced, intersects the zero height line at a small distance Oo behind the trail point 0.

Therefore, instead of, pivoting the altitude bar at the trail point or the crossing of the axes of the air speed bar and the drift bar, or in other words, the zero point for the air speed, ground speed and altitude speed, scales, according to the present invention the altitude bar is pivoted a short distance behind, above, below or in front of the trail point, for example at a false trail point 1..

. In ascertaining the point at, a number ,ofdifferentheights (say, three) M, h2, 71.3, are chosen and distances O-Hi, 0-1-12, 0-113 are set up on the altitude bar (which is diagrammatically shown at h) 111 I12 I13 n+fl T2+t2 T3+t3 respectively, where T the time of fall of the bomb in a vacuum and t the time lag (i. e.

the difierence between the actual time of fall and the time of fell in a vacuum). Some convenient air speed c is then chosen, and angles 6!, 82, 63 are set out equal to the trail angles (i. e. the angle by which the bomb as viewed from a uniformly moving aircraft app ars to trail behind the vertical) for the heights hi, 71.2, in? and the air speed c. Horizontal lines are drawn through Hi, H2, H3 intersecting the inclined lines at Pi, P2, P3. For heights above 2,500 feet these points fell upon an approximately straight line, which if produced meets the air speed bar (which is diagrammatically shown at s) at a point behind the trail point 0.

Similarly, for some greater air speed 11 points P6, P5, Pt may be found which lie on an approximately straight line which if produced intersects the line Pi--P2--P3 at a point near the trail point 0. Other lines found for other air speeds also meet at or near a common point which may be on or above or below the air speed bar and on or in front or" or behind a vertical line through the trail point.

By hinging the altitude bar at its common point, the conditions for accuracy are satisfied and a straight altitude bar maybe used instead of a curved one. The altitude bar in this case is set up at the false trail point, but the sighting points (i. e. the back sight and the fore sight) for any height above 2,500 feet form with the trail point 0 and the airspeed bar 25 the true trail angle, as GI, 62, 93 for example. Thus the correct trail angle is introduced for all such heights and for all air speed settings. Below 2,500 feet the line Pl--P2-P3 will follow the chain dotted curve shown to the trail point 0.

bomb sight. Alternatively, as shown in Figures 9 and 19, the'altitude barls rotatably mounted at 82 in a bridge 83 which is pivoted on the axis 38 of the universal joint, the bridge 93 can be retained in either an upright or horizontal position by means of spring links, one of which is indicated at 84 pivotally connected at one end to a lug 850a the bridge 83 and at the other end on the bomb sight frame 28. In both of these constructions of mounting for the altitude bar the bar may, when desired, be independently swung in a fore and aft planeinto ahorizontal position for facilitating. transport or for safety or other purposes; thus, the links 86 operate on each side of a dead centre position to yieldingly retain the; altitude barin the desired upright or horizontal position; rangement,v instead of pivoting the altitude bar at the false trail point, it may be so constructed that the back sight, when adjusted for height, moves along an axis inclined to the axis of the altitude bar.

Referring more especially to Figures 1, l2, 13,

14 and 15 m order to provide for the vector quantity of target speed, that is, the speed of the target relative to the ground, there is provided a target speed slide 86 engaging with the altitude bar 33 above its pivotal mounting and a in a lower frame on the bomb sight frame and the upper ring is pivotally mounted at $7, 88

about a transverse axis at or near the trail point in an upper frame 99. The lower ring 93 carries upstanding tongue I58 which engages between two lugs Hll on the upper ring 90 so that the upper ring is constrained to rotate with the lower ring but is tilt-able with respect to the lower-ring about its pivotal mounting 91, 9B. The lower ring 93 is rotated by means of a handle H32 (Fig. 15) which through bevel gearing Hi3 drives a pinion I04 rotatably mounted on the bomb sight frame and meshing with gear teeth on the lower ring 93. The guide bar 89 has a screw-threaded part H35 engaging in a nut Hi6 forming part of the upper slide 85, this guide bar being rotatable by means of a handle it! for adjusting the slide 86 according to target speed.

When the target speed slide 86 and the altitude bar 33 are at the centre of the rings so and 93,

zero target speed is set and the altitude bar' coincides with the axis 32 and the zero position on the air speed bar 25 or has a fixed relation thereto as described with respect tofigure 11. Distances radially from the axis 32 measure target speed and are set with reference to a target speed scale on the-guide bar 88.

When the upper ring 50 is tilted (see Figures 3 and 5) in the fore and aft plane, the altitude bar 33 is tilted therewith and correction is obtained for trail angle a: (Figure 12) This tilting of the altitude bar may be effected automatically by means of the mechanism arhusting for trail angle as previously described with reference to Figure 1.

The upper ring 90 carries two target motion direction wires 38 arranged parallel to the guide zero target speed.

In an alternative arbars 8 and 89 and provided with arrows indicating the direction of motion. When using the bombsight these wires are set in the proper sensev and parallel to the target wash-or the liLev to align the target speed slide parallel to the til rection of motion of the target. When the slides lower rings respectively the device is set for For adjustment to target speed the slide 86 is adjusted radially from the axis 32 to a position, say, represented by the vertical axis III as indicated in: Figures 12 and 15.

In the modified construction of bomb sight shown in Figures 16 and 17 the upper frame 99 is tilted to provide a correction for trail angle by means of a screw and nut gear H2 coacting between a crank on the upper frame 98 and a nut anchored on the bomb sight frame. In this 86 and 96 are at the centre of the upper and construction a rotatable handle H3 corresponding tothe handle. 32 is arranged to drive directly the lower ring 93, whereby the target motion direction wires 568 may be brought parallel to the target wash as above described.

Referring more especially to Figures 2 and 19 to 22, the compass bowl is housed in a casing lld fast on a vertical spindle 5 (Figure 2) rotatably mounted in the bomb sight frame 26 and carrying a bevel gearwhe'el H5. The spindle 28 of the mounting of the wind bar 2'l is connected through bevel gearing, ill to a spindle Ht passing through the air speed bar 25 which is tubular for this purpose. This spindle H3 has a splined end H9 carrying a bevel gear I20 in mesh with the bevel gear H6 so that the compass bowl casing is rotated according to the angular adjustment of the bar.

The bearing plate inthe form of a verge ring 12! with a glass cover 422 is formed wtih a de pending hub :23 which is screwed into the upper end of a sleeve I25 which surrounds and is rotatable on the compass bowl casing lid. The hub I23 is connected to the sleeve {24% by means of an,

interrupted screw thread lid and is locked I against rotation with respect to the sleeve by means of a spring detent I26 which'engages a recess 12? in a flange at the top of the sleeve 12$.

Thesleeve in is prevented from axial movement on the compass bowl casing by means of coacting stops or flanges on these parts. The sleeve carries a tooth rim (28 and the compass bowl casing carries a tooth rim I29, these rims being of the same diameter. A pinion I38 loose on a shaft |3| meshes with the tooth rim I28 and another pinion I32 fixed on the shaft 13! meshes with the tooth rim $29. The shaft I3! is rotatable in bearings 33 and 3 5 in the bomb sight frame and is parallel to the axis of rotation of the compass bowl.

The pinion I30 rotates with one set of members I35 of a multi-disc clutch of which the other set of intermediate members indicated at I38 rotate with the shaft Hit. The clutch mom hers which are shown in Figures 21 and 22, are

located between the upper surface of the pinion I38 anda collar i3? slidable on a square portion 138 of the shaft l3! which passes through complementary holes in the clutch members 38 so that these clutch members rotate with the shaft;

The collar [37 is normally pressed down on the clutchmembers by means of a helical spring H3 and an eccentric roller hill carried on a transverse spindle l ii engages with the collar so that by. rotation of the spindle H by means of a thumb lever M2 .the collar 13'! may be raised against the action of the spring I39 to disengage the clutch. The eccentric roller M8 is arranged so that its extreme positions he on opposite sides of the dead centre position and in the cmreme positions of the thumblever it rests on either of stops I43 and 4, so that the clutch remains inset.

A friction brake may be provided toaid in preventing displacement of the setting of the pinion I32 owing to vibration. This brake consists of a friction disc M5 on a cage I46 and pressed into engagement with the pinion I32 by aspring M7, the cage being prevented from rotation by guide pins 168 engaging in axial slots in the cage.

The bomb sight frame is preferably constructed as a casing to enclose the sleeve I24 and the gearing just described, the sleeve projecting through an aperture M9 at the top of the casing. The shaft 3! extends through the top of the casing and is provided with a handle 85!]. With this arrangement the size of the pinions in relation to the tooth rims 28 and I29 is such that a slow motion drive is imparted to the compass bowl casing and bearing plate. A tooth or other positive clutch may be employed instead of a friction clutch and the clutch may be associated with the compass bowl casing instead of with the bearing plate.

I claim:

1. A bomb sight comprising interconnected relatively adjustable members simulating to scale the triangle representing the vector quantities of air speed, wind speed and ground speed, sighting means positioned by said adjustable members and means automatically to change the position of the sighting means to allow for the trail angle of a. bomb by the adjustment of the effective length of the air speed member for air speed.

2. A bomb sight comprising interconnected relatively adjustable members simulating to scale crease or decrease the amount of adjustment in relatively adjustable members simulatingto scale the triangle representing the vector quantities of air speed, wind speed and ground speed, an upstanding altitude member, a back sight on said altitude member, a fore sight and means automatically to tilt said altitude member by the adjustment of the effective length of the air speed member to correct the sight line of said sights for the trail angle of a bomb.

4. A bomb sight comprising interconnected relatively adjustable members simulating to scale the triangle representing the vector quantities of air speed. wind speed and ground speed, sighting means positioned by said adjustable members and means automatically to change the position of the sighting means to allow for the trail angle of a bomb by the adjustment of the air speed member for air speed, a band wheel for adjusting the said air speed member and a friction brake releasable by the hand wheel for normally locking the air speed member in the adjusted position.

the engaged or disengaged position to which it is 5. A bomb sight comprising interconnected relatively adjustable members simulating to scale the triangle representing the vector quantities of ment of the air speed member, and means to vary 7 the coupling in order to correct the sighting line for bombs of different terminal velocities.

6. A bomb sight comprising interconnected relatively adjustable members simulating to scale the triangle representing the vector quantities of air speed, wind speed and ground speed, an upstanding altitude member, a back sight on said altitude member, a fore sight, which altitude member is pivotally mounted on the bomb sight at a point spaced away from the origin or trail point of the bomb sight, and means automatically to apply to change the height of the back sight relative to the fore sight by the adjustment of the air speed member. I

7. A bomb sight comprising interconnected.

relatively adjustable members simulating to scale the triangle representing the'vector quantities of air speed, wind speed and ground speed, an upstanding altitude member, a back sight on said altitude member, a fore sight, means automatically to change the height of the back sight relative to the fore sight by the adjustment of the air speed member, which altitude member is so shaped that the back sight, when adjusted for height, moves along an axis inclined to the axis of the altitude member.

8. A bomb sight comprising interconnected relatively adjustable members simulating to scale the triangle representing the vector quantities of air speed, wind speed and ground speed, sighting means positioned by said adjustable members and means automatically to change the position of the sighting means to allow for the trail angle of a bomb by the adjustment of the air speed member for air speed, and. an additional adjust able member co-relat-ed with the others and representing target speed.

9. A bomb sight comprising interconnected relatively adjustable members simulating to scale the vector diagram representing the vector quantities of air speed, wind speed, ground speed and target speed, which target speed member is pivotally mounted on the adjustable member on which ground speed is represented, and sights positioned on and movable by adjustment of said members.

10. A bomb sight comprising interconnected relatively adjustable members simulating to scale the vector diagram representing the vector quantities of air speed, Wind speed and ground speed, an upstanding altitude member, a back sight on said altitude member, and a fore sight,

which altitude member is altitude member, and a fore sight mounted on the ground speed member, which altitude member-is coupled to the ground speed member so as to be rotatable therewith about a vertical axis which is laterally movable relative to the ground speed member for correction for target speed, and is furthermore mounted for pivotal movement in the vertical plane of the ground speed member.

12. A bomb sight comprising interconnected relatively adjustable members simulating to scale the vector diagram representing the vector quantities of air speed, wind speed, ground speed and target speed, an upstanding altitude member, a slider movable along said target speed member and carrying said altitude member rotatable about a vertical axis thereon, a back sight on said altitude member and a fore sight on said ground speed member.

13. A bomb' sight comprising interconnected relatively adjustable members simulating to scale the triangle representing the vector quantities of air speed, wind speed, drift and target speed,

, which target speed member comprises upper and pic:

lower parts, said upper part being tiltable about a normally horizontal axis with respect to said lower part, an upstanding altitude member, a slider carrying said altitude member, said slider comprising two parts movable respectively along said upper and lower parts of the target speed member, a back sight on said altitude member and a fore sight on said drift member.

14. A bomb sight comprising interconnected relatively adjustable members simulating to scale the triangle representing the vector quantities of air speed, wind speed, drift and target speed,

, frame, an air speed member'adjustable in said frame, a wind speed member pivoted on said air speed member, a drift member pivoted to and slidable on said wind speed member, a lower rotatable member on the bomb sight frame,

-'means for rotating said lower rotatable member according to the direction of target movement, a'lower guide on said rotatable member, a lower slider movable along said lower guide, said-air speed -member being pivotally mounted in said lower slide, an upstanding altitude member, a universal joint connecting said altitude member to said drift member, an upper rotatable memmesses bergan upper guide thereon, an upper slide movable on said upper guide, in which upper slide said altitude member is rotatable, means for adjusting said upper slide on the upper guide according to target speed, means coupling the rotatable members for joint rotation, said upper rotatable member being mounted in ,a tiltable frame, a back sight adjustable on said altitude member, a fore sight, and means automatically to tilt said frame by the adjustment of said air speed member for air speed in order to apply a correction of the sighting line through said sights for trail angle.

16. A bomb sight comprising a compass having its bowl mounted to rotate about a vertical axis, a wind member geared to the bowl, a bearing plate rotatable at the top of the bowl, a toothed gear secured to the bowl, a pinion fast'on a rotatable adjusting shaft and meshing with the toothed gear, a second toothed gear secured to the bearing plate, a second pinion connected to the adjustingzshaft by' a disengageable clutch and meshing with the second toothed gear.

17. A bomb sight comprising relatively adjustable members simulating to scale the triangle representing the vector quantities of air speed, ,wind speed and ground speed, an upstanding altitudemembers, a back sight on said altitude member, a fore sight, which altitude member is pivotally mounted on the bomb sight "at a point the bomb sight, said pivotal point corresponding in scale to the point of intersection of straight lines on a graph on which known trail angles have been plotted from varying air speeds and altitudes, said straight lines passing through points on the graph where lines representing trail ang cs, air speeds and altitudes intersect, and means automatically to change the height of the back sight relative to the fore sight by the adjustment of the air speed member.

18. A bomb sight comprising interconnected relatively adjustable members simulating to scale the vector diagram representing the vector quantitles of air speed, wind speed, ground speed and target speed, which target speed member is pivoted to the ground speed member at a point speed member, and a universal joint which couples the altitude member to the drift member- EDWARD CECH HQRSLEY,

spaced away from the origin or trail point of 

